cdevvp
cdevvp(cndev, &cn_devvp);
if (cdevvp(rawdev, &vn)) {
if ((error = cdevvp(getnulldev(), &vp)) != 0) {
error = cdevvp(makedev(major(vp->v_rdev),
if (cdevvp(rawdev, &vn)) {
int cdevvp(dev_t, struct vnode **);